As a manufacturing of a sheet in accordance with the inflation extrusion molding technique, there has been a technique using guide rollers. This technique includes transferring a cylindrically inflated sheet extruded from an extruder while flattening the same by means of stabilizers including a plurality of rows of guide rollers. Since the technique enables efficient manufacture of sheets, the technique has hitherto, widely been utilized.
However, unlike manufacture of an ordinary sheet, in case where a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one side thereof is manufactured by the inflation extrusion molding method, when an attempt is made to convey a cylindrically-shaped pressure-sensitive adhesive sheet in the middle of inflating into a cylindrical shape while flattening the same with a plurality of rows of guide rollers, a mismatch often arises between a traveling direction of the cylindrically-shaped pressure-sensitive adhesive sheet and a rotating-direction of the guide rollers. It is difficult for the cylindrically-shaped pressure-sensitive adhesive sheet to correct the mismatch by sliding over surfaces of the guide rollers. Consequently, a surface of the pressure-sensitive adhesive tape thus obtained sometimes becomes wavy or wrinkled.
Accordingly, another technique has been developed as an advanced version of the above-mentioned technique. This technique makes it possible to prevent wrinkles, and the like, which would otherwise arise when a resin material, such as a pressure-sensitive adhesive sheet, extruded in accordance with the inflation technique is flatly folded (see JP-A-2005-111980).
According to this technique, each of the stabilizers is built from a plurality of rows of rollers in which a plurality of rollers are arranged in a row, and directions of the respective rollers of the stabilizer are aligned to a substantially same direction where a resin material spreads when deformed into a flattened elliptical shape.
It thereby becomes possible to readily deform a resin material of a pressure-sensitive adhesive sheet extruded in accordance with the inflation method into a flattened elliptical shape and significantly prevent wrinkles, and the like, which would otherwise arise after the pressure-sensitive adhesive sheet is folded.
This technique has made it possible to significantly prevent occurrence of wrinkles, and the like, which would otherwise be caused after the sheet has been folded, as compared with the above-mentioned technique. As mentioned above, even when a slight difference exists between the traveling direction of the sheet and the rotating-direction of the rollers, in case of a pressure-sensitive adhesive sheet exhibiting small pressure-sensitive adhesive force, it slides over the rollers, whereby a slight correction is made to the difference so that the sheet can run in its original traveling direction. Thus, the drawback has been resolved.
When an adherend is flat, there arises no problems with this technique. However, when the adherend has a rough surface, or the like, there arises a necessity for enhancing adhesiveness of the pressure-sensitive adhesive sheet. When a pressure-sensitive adhesive exhibiting enhanced adhesiveness is made on the outermost surface of the sheet, the pressure-sensitive adhesive makes the sheet difficult to slide over the rollers, so that the direction of the sheet cannot be corrected. Therefore, the sheet becomes more difficult to run in the original sheet traveling direction, and occurrence of wrinkles is found here and there in the resultant sheet.